cbodotnetup 0.3.0 - verified Community Build SDK manager

SDK-free NativeAOT installer for qualified Community Build of .NET SDKs. Verify the current project-signed installation catalog and its independently pinned OpenPGP key. Linux glibc x64/AArch64; Ubuntu24.04, Debian13, Fedora45 and Rocky9.8. Qualified SDKs:10.0.403,9.0.123,8.0.133,7.0.120,6.0.136. Native runtime 10.0.14; the SDK payload stays unchanged. Per-user roots preserve official and package-managed commands. Each binary has exact signed native runtime/project license and third-party notices in its adjacent .LICENSE.txt asset. Version 0.3 adds offline global.json SDK selection from verified owned installations, exact explicit-version and series-alias precedence, and bound managed CLI/MSBuild execution. Missing SDKs require explicit installation; project and shell files stay unchanged. The versioned schema2 catalog retains neutral SDK archive names; the schema1 feed keeps 0.1 clients able to self-update. Build/source records are retained; current signed catalog qualification is published separately. This release does not replace the latest SDK download.